The BiP protein and the endoplasmic reticulum of Schizosaccharomyces pombe: fate of the nuclear envelope during cell division.

A polyclonal antibody was raised to the C-terminal region of fission yeast BiP. The use of this antibody for immunoprecipitation, western blotting and immunofluorescence has confirmed and extended the observations made previously with an epitope-tagged BiP molecule. A fraction of BiP protein is glycosylated in Schizosaccharomyces pombe cells. Pulse-chase experiments showed that this modification occurs rapidly upon synthesis and that the extent of glycosylation does not then change with time. BiP protein is induced by elevated temperatures and by treatment with tunicamycin. The antibody cross-reacts with proteins of similar molecular weight in the yeasts Kluyveromyces lactis and Schizosaccharomyces japonicus. Immunofluorescence of BiP has been used to follow the behaviour of the ER and in particular the nuclear envelope through the cell cycle.